Matching networks that utilize tunable components can be used in cellular telephone handsets, specifically in handset antenna applications, for matching variable loads and/or optimizing performance at multiple frequencies. Antenna tuner performance can be highly dependent, however, on finding the optimum settings of the individual tunable components in the matching network. Deviations from the optimum values for one or more components can lead to less than desired total radiated power (TRP) and/or total isotropic sensitivity (TIS) performance in the application.
Once source of such deviation from optimum values can be that varying performance of tunable capacitors (i.e., AC) between foundries, lots, and wafers can result in part-to-part variation, which can typically be around 10% or more. Such manufacturing variances are inherent to the process in which the capacitors are manufactured, but they can lead to unwanted variations in capacitance (and hence TRP/TIS) between devices, even when programmed with identical tuning words. Furthermore, open loop antenna tuner applications generally require fairly accurate capacitor performance (e.g., within about 5%), making the manufacturing variances even more problematic.
One option to address this variation is to maintain strict tolerances on the production of these devices, allowing only those that meet particular performance parameters to be used in the antenna tuner. Testing in this way to sort for tight tolerance parts, however, can result in poor yield, which can dramatically drive up the production costs for such devices. Alternatively, device manufacturers can compensate for poor component performance by non-volatile memory to calibrate the performance of a component die. Such memory-based corrections are typically added on before total system integration, and thus deviations from optimal performance can still occur as a result of other factors (e.g., inductor tolerances, variances in component mounting).
As a result, it would be desirable for systems and methods for manufacturing and/or configuring tunable matching network components that combine good yield with good open loop application performance.